As the trend has pushed semiconductor devices to smaller and smaller sizes, different patterning techniques have arisen. These techniques include directed self-assembly (DSA), spacer defined multiple patterning, extreme ultraviolet lithography (EUV), and EUV combined with spacer defined multiple patterning.
Spacer defined multiple patterning utilizes spacer features formed at the sides of a core of another material. The core material is removed to leave free-standing spacers, which may subsequently be used as masking features for patterning underlying material. Undesirably, the edges of the free-standing spacers may be rough, which may provide poor quality patterning results.
Accordingly, there is a need for methods for patterning small, high quality features.